Hard to say, as you're feeling pretty shit for the doctors to put you on them.
Can often feel worse at first as you get used to the effect. Can take weeks before they start to do their thing. Think I was like a zombie at first!
Take after food and in the morning.
It has a long half life iirc.
Since I've been on them, mornings can be utterly shit for an hour or two until I come round, or can seem normal. This is having the sensation that the inside of your head is bouncing about. Like being awoken from a very deep sleep suddenly.
Always better for a good sleep though, and no disturbance. Not sure if this is a side effect, the underlying illness, or the affect of other meds (epilepsy).
The initial period is by far the worst though, not everyone manages it and needs to come off or try something else.